Question

A 3 kgblock measures5 cm by 10 cm by 20cm. When it slides on a 10cm by 20 cmface, it moves with constant speed when pulled horizontally by a force whose magnitude 3N is. How big a horizontal force must be applied to pull it with constant speed of it slides on a 5 cm by 20 cm face?

Short answer

A horizontal Force is 3N.

Step-by-step solution

Identification of the given data

The mass of a block is 3 kg.

The magnitude of horizontal force is 3 N.

The size of the box is 5 cm b y 10 cm by 20 cm.

The size of the box in which the box sliding is 10 cm by 20 cm

Determination of a horizontal force must be applied to pull it with constant speed

For constant speed, acceleration will be zero.

So that

Horizontal force$F=\mu mg$

Where,

F = 3N

$$\begin{gathered} \mu =coefficientoffriction \\ m=massofablock\Rightarrow 3kg \\ g=accelerationduetogravity\Rightarrow 9.81m/s^2 \\ 3=\mu \times 3\times 9.81 \\ \mu =0.101 \end{gathered}$$

And coefficient of friction does not depend on surface area of contact. So the horizontal force must be applied to pull it with constant speed of it slides on a 5cm by 20 cm face will be 3N. Because mass of block is same and coefficient of friction is same.